%%% ====================================================================
%%% @LaTeX-doc-source-file{
%%% filename = "snapshot.dtx",
%%% version = "1.14",
%%% date = "2002/03/05",
%%% time = "15:29:00 EST",
%%% checksum = "39090 807 3449 29761",
%%% author = "American Mathematical Society",
%%% copyright = "Copyright 2001 American Mathematical Society,
%%% all rights reserved. Copying of this file is
%%% authorized only if either:
%%% (1) you make absolutely no changes to your copy,
%%% including name; OR
%%% (2) if you do make changes, you first rename it
%%% to some other name.",
%%% address = "American Mathematical Society,
%%% Electronic Products and Services,
%%% PO Box 6248,
%%% Providence, RI 02940,
%%% USA",
%%% email = "tech-support@ams.org",
%%% URL = "http://www.ams.org/",
%%% supported = "yes",
%%% keywords = "version, compatibility, dependencies, LaTeX",
%%% abstract = "This package provides a way for a LaTeX
%%% document to specify, for each external file
%%% on which the document depends, which version
%%% is required to guarantee output fidelity.",
%%% docstring = "The checksum field above contains a CRC-16
%%% checksum as the first value, followed by the
%%% equivalent of the standard UNIX wc (word
%%% count) utility output of lines, words, and
%%% characters. This is produced by Robert
%%% Solovay's checksum utility.",
%%% }
%%% ====================================================================
% \iffalse
%
\NeedsTeXFormat{LaTeX2e}
\documentclass{amsdtx}
\providecommand{\qq}[1]{\textquotedblleft#1\textquotedblright}
\providecommand{\mdash}{\textemdash}
\begin{document}
\title{The \pkg{snapshot} package}
\author{American Mathematical Society\\Michael Downes}
\date{Version \fileversion, \filedate}
\hDocInput{snapshot.dtx}
\end{document}
%
% \fi
%
% \MakeShortVerb{\|}
%
% \maketitle
% \section{Introduction}
%
% The \pkg{snapshot} package helps the owner of a \LaTeX{} document
% obtain a list of the external dependencies of the document, in a
% form that can be embedded at the top of the document. To put it
% another way, it provides a snapshot of the current processing
% context of the document, insofar as it can be determined from
% inside \LaTeX{}.
%
% If a document contains such a dependency list, then it becomes
% possible to arrange that the document be processed always with the
% same versions of everything, in order to ensure the same output.
% This could be useful for someone wanting to keep a \LaTeX{}
% document on hand and consistently reproduce an identical DVI file
% from it, on the fly; or for someone wanting to shield a document
% during the final stages of its production cycle from unexpected
% side effects of routine upgrades to the \TeX{} system.
%
% Normal usage of the \pkg{snapshot} package involves the following
% steps:
% \begin{enumerate}
% \item Add a \cn{RequirePackage} statement at the top of the
% document:
% \begin{verbatim}
% \RequirePackage{snapshot}
% \documentclass{article}
% ...
% \end{verbatim}
%
% \item Run \latex/ on the document. This will produce a dependency
% list in a file \verb'\jobname.dep'.
%
% \item Insert the \fn{.dep} file at the top of the document, before
% \cn{documentclass}. The following example shows what you would end
% up with for a document that used the article documentclass and the
% graphicx package:
% \begin{verbatim}
% \RequirePackage{snapshot}[1999/11/03]
% \RequireVersions{
% *{application}{TeX} {1990/03/25 v3.x}
% *{format} {LaTeX2e} {1999/06/01 v2.e}
% *{package}{snapshot} {1999/11/03 v1.03}
% *{class} {article} {1999/01/07 v1.4a}
% *{file} {size10.clo} {1999/01/07 v1.4a}
% *{package}{graphicx} {1999/02/16 v1.0f}
% *{package}{keyval} {1999/03/16 v1.13}
% *{package}{graphics} {1999/02/16 v1.0l}
% *{package}{trig} {1999/03/16 v1.09}
% *{file} {graphics.cfg}{0000/00/00 v0.0}
% *{file} {dvips.def} {1999/02/16 v3.0i}
% }
% \documentclass{article}
% \usepackage{graphicx}
% ...
% \end{verbatim}
% \end{enumerate}
%
% The package option \opt{log} will cause the dependency list to
% appear in the \latex/ log file instead of in a separate \fn{.dep}
% file:
% \begin{verbatim}
% \RequirePackage[log]{snapshot}
% \end{verbatim}
%
% Making the necessary arrangements to ensure that future \latex/
% runs of the document actually call in the specified versions is a
% separate problem. The \pkg{snapshot} package only provides a way to
% generate the dependency list. However, the \cn{RequireVersions}
% statement does record the given information in a form that can be
% accessed from within \latex/. (It is for this purpose that it is not
% simply a comment.) In principle a package could be set up so that a
% later version would automatically attempt to emulate an earlier
% version if an earlier version was specified\mdash much as \latex/
% currently switches to 2.09 compatibility mode if it sees
% \cn{documentstyle} instead of \cn{documentclass}.
%
% For maximum reliability font checksums should also be reported in
% the dependency list, but standard \tex/ 3.x does not provide direct
% access to font checksums for macro programmers. This information
% could be added by a separate script that scans the DVI file.
%
% When a graphics file is read in by a \latex/ document using the
% standard \cn{includegraphics} command, it gets a dummy version
% number string of
%\begin{verbatim}
%Graphics file (type foo)
%\end{verbatim}
% where foo is typically \texttt{eps}. This is with the current
% version of the \pkg{graphics} package (at the time of this writing:
% 1999/02/16 v1.0l). What this means in practice is that all graphics
% files will have their snapshot date and version number recorded as
%\begin{verbatim}
%Graphics v0.0
%\end{verbatim}
% and will always compare equal (the string ``Graphics'' will be used
% in place of a date, but since comparison is done with \cs{ifx} it
% doesn't make any real difference).
%
% It would be possible, for \fn{.eps} files at least, to read the
% CreationDate comment that is normally included in the file header
% and use that as the basis of comparison. Recording the bounding box
% numbers instead of a dummy version number would also be a possibly
% useful stratagem. But I have left these possibilities untouched for
% the time being [mjd,2001-05-14].
%
% \DescribeMacro{\RequireVersions} The \cn{RequireVersions} command
% scans its argument for file names and associated version number
% information. The syntax of a version line for a particular file is
% \begin{quote}
% \verb'*{' \emph{file type} \verb'}{' \emph{file name} \verb'}{'
% \emph{version info} \verb'}'
% \end{quote}
% In other words, the \verb'*' character in this context is like a
% command that takes three arguments. The extension part of the
% file name should be omitted in the second argument, except when the
% file type is \fn{file} (following the conventions of \latex/'s
% \cn{ProvidesPackage} and \cn{ProvidesFile} commands). The most
% commonly used file types are as follows.
% \begin{description}
% \item[class] A \latex/ documentclass file.
% \item[package] A \latex/ package file.
% \item[tfm] A \tex/ font metric file. In this case the \qq{version
% number} is the checksum, and unless you are using an extended
% version of \tex/ this information is not accessible from inside
% \latex/, so it must be filled in by an outside process.
% By default, font metric files are not listed in the dependency list
% since the checksum info is not available. There is a package option
% \opt{tfm} to turn on the logging of metric files. (Not yet
% implemented [mjd,1999/09/23])
%
% \item[format] This is almost always \fn{LaTeX2e}. Other possibilities
% would be \fn{elatex} or \fn{lambda}. The information comes from
% \cs{fmtname}.
% \item[application] This is usually \fn{TeX} with version number
% \fn{3.x}. From inside \latex/ there is no reliable way to get the
% exact version number (one could check to see if version 2.x is in
% use, but this is unlikely to be relevant, nowadays, so I have not
% bothered).
% \item[file] None of the above: some other file of miscellaneous type,
% e.g., \fn{.clo}, \fn{.cfg}, \fn{.tex}, or \fn{.def}.
% \end{description}
%
% The \cn{RequireVersions} command can be given an optional
% \qq{ident} argument, similar to the argument of a \cn{label}
% command. This is not used internally but it could be used to
% assign a label to particular groups of files in case that helps
% with external processing.
%
% \section{Warning and error options}
%
% If the \pkg{snapshot} package is invoked with the \opt{error}
% option \emph{and also} the document contains a \cn{RequireVersions}
% statement, then each subsequent \cn{ProvidesFile},
% \cn{ProvidesPackage}, and \cn{ProvidesClass} statement will compare
% date and version number information with the corresponding
% information from the \cn{RequireVersions} statement and give an
% error message if a mismatch is detected. With the \opt{warning}
% option you get warnings instead of errors. By default both the date
% and the version number are compared; this behavior can be modified,
% however, by giving additional options:
% \begin{description}
% \item[date] compare only dates,
% \item[version] compare only version numbers,
% \item[major-version] use only the major version number when
% comparing.
% \end{description}
%
% \textbf{Note:} A file that doesn't have any sort of
% \cn{ProvidesFile} or \cn{ProvidesPackage} statement in it will show
% up in the dependency list, with a dummy date and version number of
% 0000/00/00 v0.0, but there is no way, of course, to give any
% meaningful warning or error message about version mismatches for
% such a file.
%
% \StopEventually{}
%
% \section{Implementation}
% Standard declaration of package name and date.
% \begin{macrocode}
\NeedsTeXFormat{LaTeX2e}[1994/12/01]
\ProvidesPackage{snapshot}[2002/03/05 v1.14]
% \end{macrocode}
%
% \begin{macrocode}
\let\@xp\expandafter \let\@nx\noexpand
% \end{macrocode}
%
% Calling the \pkg{snapshot} package in a document causes \latex/ to
% list the file names and versions in the \tex/ log or in a \fn{.dep}
% file, so that the information may be easily copied into the
% document file. The list so generated is nothing more than a slight
% adaptation of the output from \latex/'s \cn{listfiles} command; it
% puts essentially the same information into a slightly more
% structured form so that it will be easier to use.
%
% For the standard mechanisms that are already built into \latex/
% (e.g., the handling of the second optional argument of
% \cs{LoadClass}), the de facto \qq{version number} is the
% \emph{date} given in the optional argument of a \cn{ProvidesClass}
% or similar command. Even though most \cn{ProvidesWhatever} commands
% also give something that follows the usual form of version
% numbers\mdash a string of the form \verb'v2.3'\mdash this is only a
% convention, not used internally by \latex/, and the identification
% string of a random loaded file is not guaranteed to include it. The
% \pkg{snapshot} package copies both pieces of information if
% available; if the second piece is not present, a dummy number
% \verb'0.0' is supplied. Similarly, files that don't include any
% \cn{ProvidesWhatever} statement will get a dummy date of
% \verb'0000/00/00'; \tex/ system administrators who want to ensure
% maximal accuracy of the snapshot information should therefore make
% it a practice to use \cn{ProvidesFile} in \fn{.cfg} files and other
% local files that might have an impact on the output fidelity of
% their documents.
%
% \begin{macro}{\RequireVersions}
%
% Optional argument of \cn{RequireVersions} allows assigning a name to a
% particular collection of files. This might be useful for setting a
% \tex/ inputs path.
% \begin{macrocode}
\newcommand{\RequireVersions}[2][]{%
\let\snap@check\snap@compare@versions
\let\snap@selfcheck\snap@selfcheck@a
\@ifnextchar *\snap@store@version\snap@store@error#2*{end}{}{}%
}
\@onlypreamble\RequireVersions
% \end{macrocode}
%
% \begin{macrocode}
\def\snap@store@error#1{%
\PackageError{snapshot}{Expected '*' here, not '#1'}\@ehc
}
\@onlypreamble\snap@store@error
% \end{macrocode}
%
% \begin{macrocode}
\def\snap@store@version #1#2#3#4{%
\@xp\snap@store@b\csname snapx@#2\endcsname{#2}{#3}{#4}%
}
\@onlypreamble\snap@store@version
% \end{macrocode}
%
% \begin{macrocode}
\def\@fmtextension{fmt}
\def\@tfmextension{tfm}
\edef\snapx@package{.\@pkgextension}
\edef\snapx@class{.\@clsextension}
\edef\snapx@format{.\@fmtextension}
\edef\snapx@tfm{.\@tfmextension}
\long\def\snapx@application{}
\let\snap@file=\@empty
\let\snapx@end\@@end
% \end{macrocode}
%
% For a package named \fn{foo.sty}, this function defines
% \cs{rqv@foo.sty} to hold the date and version information.
% \begin{macrocode}
\def\snap@store@b#1#2#3#4{%
\ifx#1\snapx@end
\@xp\@gobblefour
\else
\ifx#1\relax \let#1\@empty\fi
\def\@tempa##1 ##2 ##3\@nil{##1 ##2}%
% \end{macrocode}
%
% \begin{macrocode}
\ifx#1\snapx@application
\else
\xdef\rqv@list{\rqv@list
\ifx\@empty\rqv@list\else,\fi
#3#1%
}%
\fi
\@xp\xdef\csname rqv@#3#1\endcsname{\@tempa#4 v?.? ? \relax\@nil}%
\ifx#1\snapx@format \snap@check{#3.fmt}%
\else \snap@selfcheck{#3.sty}%
\fi
\fi
\@ifnextchar *\snap@store@version\snap@store@error
}
\@onlypreamble\snap@store@b
% \end{macrocode}
% \end{macro}
%
% Default setup is geared to write the dependency list to a \fn{.dep}
% file. The option \opt{log} means write it to the \tex/ log instead.
% \begin{macrocode}
\def\snap@write{\immediate\write\snap@out}
\let\snap@out\sixt@@n % fallback, probably never used
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{dep}{%
\def\snap@write{\immediate\write\snap@out}%
}
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{log}{%
\let\snap@write\typeout
}
% \end{macrocode}
%
% The purpose of the `test' option is to support a separate testing
% procedure that resolves file names. If the \cs{RequireVersions}
% data is extracted to a separate file, and
%\begin{verbatim}
%\RequirePackage[test]{snapshot}
%\end{verbatim}
% is added at the top, then the file can be run as a small separate
% \LaTeX{} job whose sole purpose is to produce in the log file a
% nice list of fully resolved file names. A limited, but
% system-independent variant of the \fn{kpsewhich} idea.
%
% \begin{macrocode}
\let\snap@fake@b\relax
\DeclareOption{test}{%
\def\snap@fake@b{\endinput \futurelet\@let@token\snap@ignoline}%
}
% \end{macrocode}
%
% For each font used by a document, we would like to list the
% \fn{.tfm} file name and checksum. If \tex/ provided a
% \cn{fontchecksum} primitive similar to \cn{fontname} that could be
% used to get the checksum of any font, it would just about be
% feasible to do this entirely from within \latex/. As a partial
% solution we could at least generate the list of font file names, to
% make it easier for an external utility to add the checksums.
%
% In practice, extracting font names and checksums from the \fn{.dvi}
% file will probably work well enough, leaving no work to be done by
% the \pkg{snapshot} package in this area. But theoretically speaking
% the output of a document could be affected by font metric files
% that are loaded during \latex/ processing but that do not show up
% in the \fn{.dvi} file.
% \begin{macrocode}
\DeclareOption{tfm}{%
\typeout{Option 'tfm' not implemented yet [1999/09/23]}%
}
% \end{macrocode}
%
% Warnings and errors.
% \begin{macrocode}
\def\snap@mismatch@warning#1#2#3{\PackageWarningNoLine{#1}{#2}}
\def\snap@mismatch{\snap@mismatch@warning}
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{error}{%
\def\snap@mismatch{\PackageError}%
\ifx\snap@select\@empty \let\snap@select\snap@select@all \fi
}
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{warning}{%
\def\snap@mismatch{\snap@mismatch@warning}%
\ifx\snap@select\@empty \let\snap@select\snap@select@all \fi
}
% \end{macrocode}
%
% Because the exact form of the version number is not mandated by
% LaTeX, just take the first two ``words'' delimited by spaces. And
% take a little extra care to properly handle multiple spaces between
% the words.
% \begin{macrocode}
\def\snap@select@all#1#2 #3#4 #5\@nil{#1#2 #3#4}
\let\snap@select\@empty
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{date}{%
\def\snap@select#1#2 #3\@nil{#1#2}%
}
% \end{macrocode}
%
% \begin{macrocode}
\def\snap@select@version#1{%
\ifodd 0#11 \@xp\snap@sva\@xp#1\else\@xp\snap@select@version\fi
}
\def\snap@sva#1.#2 #3\@nil{#1.#2}
\def\snap@select@major#1{%
\ifodd 0#11 \@xp\snap@svm\@xp#1\else\@xp\snap@select@major\fi
}
\def\snap@svm#1.#2\@nil{#1}
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{version}{%
\def\snap@select#1#2 #3{\snap@select@version #3}%
}
% \end{macrocode}
%
% \begin{macrocode}
\DeclareOption{major-version}{%
\def\snap@select#1#2 #3{\snap@select@major #3}%
}
% \end{macrocode}
%
% \begin{macrocode}
\ProcessOptions\par
% \end{macrocode}
%
% We need the following patch to make up for the fact that
% \cs{@pkgextension} and \cs{@clsextension} are marked in the \latex/
% kernel as \qq{only preamble}.
% \begin{macrocode}
\edef\snap@restore@extensions{%
\def\@nx\@pkgextension{\@pkgextension}%
\def\@nx\@clsextension{\@clsextension}%
}
% \end{macrocode}
%
% Pad filename strings out to 8+3 length so that the list will look
% pretty.
% \begin{macrocode}
\def\snap@pad#1#2#3#4#5#6#7#8#9{\snap@pad@a{#1#2#3#4#5#6#7#8#9}}
\def\snap@pad@a#1#2#3#4#5\@nil{\snap@pad@b#1#2#3#4\space\@nil}
\def\snap@pad@b#1\space#2\@nil#3{\def#3{#2}}
% \end{macrocode}
%
% First stage: discard leading spaces before the first and second
% nonspace strings in the argument. Take the first nonspace string as
% the date. Since we only do equal/not-equal testing on dates, it
% does not seem essential to test if it is really a valid date string
% or not (yyyy/mm/dd).
% \begin{macrocode}
\def\snap@trim@version#1#2 #3{#1#2 \snap@trim@b #3}
% \end{macrocode}
% Second stage: Scan for a version number. In order to handle some
% idiosyncratic cases, such as url.sty version 1.4, we can't simply
% take the second nonspace string as the version number but need to
% look for a leading digit.
% \begin{macrocode}
\def\snap@trim@b#1{\ifodd 0#11 v#1\@xp\snap@trim@c\fi \snap@trim@b}
% \end{macrocode}
% Arg 1 here is \cs{snap@trim@b}, which we just need to discard.
% \begin{macrocode}
\def\snap@trim@c#1#2 #3\@nil{#2}
% \end{macrocode}
%
% \begin{macrocode}
\let\rqv@list=\@empty
% \end{macrocode}
%
% If \verb'\fmtname.fmt' is not already in the file list, add it.
% \begin{macrocode}
\edef\@tempc#1\fmtname{#1\fmtname}\@tempc
\def\@tempa#1,\fmtname.fmt,#2#3\@nil{#2}
\edef\@tempb{\@nx\@tempa,\@filelist,\fmtname.fmt,}
\if ?\@tempb?\@nil
\edef\@filelist{\fmtname.fmt,\@filelist}%
\def\@tempc{LaTeX2e}%
\@xp\edef\csname ver@\fmtname.fmt\endcsname{%
\fmtversion\space
v\ifx\@tempc\fmtname 2.e\else ?.?\fi
}%
\fi
\listfiles
\def\@dofilelist{%
\snap@restore@extensions
\ifx\rqv@list\@empty
\else \rqv@compare@lists
\fi
\ifx\snap@write\typeout
\else
\newwrite\snap@out
\immediate\openout\snap@out=\jobname.dep \relax
\fi
\snap@write{\string\RequireVersions\@charlb}%
% \end{macrocode}
% Since the exact version number of \TeX{} is not normally accessible
% from inside \latex/, we use a nominal date of 1990/03/25, which is
% when version 3.0 of \fn{tex.web} was released by Knuth.
% \begin{macrocode}
\snap@write{\space\space *{application}{TeX}%
\space\space\space\space\space{1990/03/25 v3.x}}%
\@for\@currname:=\@filelist\do{%
\filename@parse\@currname
\ifx\filename@ext\relax
\def\@tempa{file}\def\@tempd{.tex}\def\filename@ext{tex}%
\def\@tempb{~~~}%
\else\ifx\filename@ext\@pkgextension
\def\@tempa{package}\let\@tempd\@empty
\def\@tempb{}%
\else\ifx\filename@ext\@clsextension
\def\@tempa{class}\let\@tempd\@empty
\def\@tempb{~~}%
\else\ifx\filename@ext\@fmtextension
\def\@tempa{format}\let\@tempd\@empty
\def\@tempb{~}%
\else\ifx\filename@ext\@tfmextension
\def\@tempa{tfm}\let\@tempd\@empty
\def\@tempb{~~~~}%
\else
\def\@tempa{file}\edef\@tempd{.\filename@ext}%
\def\@tempb{~~~}%
\fi\fi\fi\fi\fi
\@xp\let\@xp\@tempe
\csname ver@\filename@base.\filename@ext\endcsname
% \end{macrocode}
% If a file contains just \verb'\ProvidesFoo{xyz}' without \emph{any}
% optional argument, then \cs{ver@xyz} ends up empty. Resetting it to
% \cs{relax} is the easiest way to get the fallback version
% number in that case also.
% \begin{macrocode}
\ifx\@tempe\@empty \let\@tempe\relax \fi
\edef\@tempe{%
\ifx\@tempe\relax 0000/00/00 v0.0%
\else
\@xp\@xp\@xp\snap@trim@version\@xp\@tempe\space v0.0 v0.0 \@nil
\fi
}%
\edef\@tempc{\filename@area\filename@base\@tempd}% full file name
\@xp\snap@pad\@tempc\space~~~~~~~~~~~~~~~~\@nil\@tempd
\begingroup \let~\space
\snap@write{\space\space *{\@tempa}\@tempb{\@tempc}\@tempd{\@tempe}}%
\endgroup
}%
\snap@write{\@charrb}%
\ifx\snap@write\typeout
\else \immediate\closeout\snap@out
\typeout{Dependency list written on \jobname.dep.}%
\fi
}%
% \end{macrocode}
%
% The \cs{rqv@compare@lists} function checks to see if any files
% are found only in the RequireVersions list or only in
% \cs{@filelist}. To see which files are only in \cs{@filelist}, we
% map the \cs{rqv@condense} function across both lists, reinitializing
% \cs{L} (used here as a scratch variable) in between. As a side
% effect this leaves the desired file names in \cs{L}. Then the same
% process with the order of the lists reversed tells us which ones
% are only in \cs{rqv@list}.
% \begin{macrocode}
\def\rqv@condense#1,{%
\if ,#1,%
\else
\@xp\ifx\csname ver@#1\endcsname\N
\else
\edef\L{\L,#1}%
\@xp\let\csname ver@#1\endcsname=\N
\fi
\fi
\rqv@condense
}
% \end{macrocode}
%
% \begin{macrocode}
\def\rqv@compare@lists{%
\begingroup
\def\N{1}\let\L=\@gobble
\@xp\rqv@condense \rqv@list,TeX,{,\relax\@xp\@gobbletwo\@xp},%
\ifx\L\@gobble\let\L\@empty\fi
\let\rqv@list=\L
\let\L=\@gobble
\@xp\rqv@condense \@filelist,{,\relax\@xp\@gobbletwo\@xp},%
\ifx\L\@gobble\let\L\@empty\fi
\@for\@currname:=\L\do{%
\snap@mismatch{snapshot}{^^J%
File \@currname\space loaded though not in
\noexpand\RequireVersions list%
}\@ehc
}%
\def\N{2}\let\L=\@gobble
\@xp\rqv@condense\@filelist,TeX,{,\relax\@xp\@gobbletwo\@xp},%
\let\L=\@gobble
\@xp\rqv@condense\rqv@list,{,\relax\@xp\@gobbletwo\@xp},%
\ifx\L\@gobble\let\L\@empty\fi
\@for\@currname:=\L\do{%
\snap@mismatch{snapshot}{^^J%
File \@currname\space [\csname rqv@\@currname\endcsname]
required but not loaded%
}\@ehc
}%
\endgroup
}
% \end{macrocode}
%
% See the documentation above for the `test' option.
% \begin{macrocode}
\begingroup \catcode\endlinechar=12\relax %
\long\gdef\snap@ignoline#1
{}\endgroup %
% \end{macrocode}
%
% \begin{macrocode}
\def\snap@fake@input#1#2#3#4{%
\ifx#1\snapx@end
\aftergroup\@@end \@xp\@gobblefour
\else
\ifx#1\snapx@format
\else
\message{^^J}%
\@xp\snap@fake@b\@@input #3#1\relax
\fi
\fi
\@ifnextchar *\snap@store@version\snap@store@error
}
% \end{macrocode}
%
% \begin{macrocode}
\newcommand{\rqvTest}[2][]{%
\begingroup \catcode\endlinechar=12
\catcode`\%=12 \catcode`\{=12 \catcode`\}=12\relax
% \end{macrocode}
% Since \cs{snap@fake@input} just compares \cs{snapx@foo} with
% \cs{ifx}, making \cs{snapx@application}
% and \cs{snapx@tfm} compare equal to \cs{snap@format}
% ensures that only one comparison is needed to tell if
% we shouldn't attempt to input the current file type.
% \begin{macrocode}
\let\snapx@application=\snapx@format \let\snapx@tfm=\snap@format
\@ifnextchar *\snap@store@version\snap@store@error#2*{end}{}{}%
\endgroup
}
% \end{macrocode}
%
% \begin{macrocode}
\@ifundefined{snap@fake@b}{}{%
\let\snap@store@b\snap@fake@input
\let\RequireVersions\rqvTest
}
% \end{macrocode}
%
% Compensate for a bug in old versions of \fn{amsgen.sty}. This is a
% little tricky.
%
% Old version: \cs{ver@amsgen}=1996/10/29 v1.2b
%
% New version: \cs{ver@amsgen.sty}=1999/11/30 v2.0
% \begin{macrocode}
%\@namedef{ver@amsgen.sty}{1996/10/29 v1.2b}
\AtBeginDocument{%
\@ifundefined{ver@amsgen}{}{%
\@xp\let\csname ver@amsgen.sty\@xp\endcsname
\csname ver@amsgen\endcsname
}%
}
% \end{macrocode}
%
% Terminate here without touching \LaTeX{} internals, unless
% one of the relevant snapshot options was chosen.
% \begin{macrocode}
\let\snap@compare@versions\@gobble \let\snap@check\@gobble
\let\snap@selfcheck\@gobble \let\snap@selfcheck@a\@gobble
\ifx\snap@select\@empty \endinput \fi
% \end{macrocode}
%
% \begin{macrocode}
\begingroup \catcode`\.=11\relax
\gdef\snap@selfcheck@b#1\rqv@snapshot.sty#2#3\@nil{T#2}
\gdef\snap@selfcheck@a#1{%
\if\@xp\snap@selfcheck@b\csname rqv@#1\endcsname T%
\rqv@snapshot.sty F\@nil
\snap@check{#1}%
\fi
}
\endgroup
% \end{macrocode}
%
% \begin{macrocode}
\def\@nofmt#1.fmt.#2 {#1 }
% \end{macrocode}
%
% \begin{macrocode}
\def\snap@mismatch@a#1#2#3{%
\snap@mismatch{snapshot}{^^J%
\space\space Required version #2 of \@nofmt#1.fmt. and^^J%
\space\space provided version #3 do not match%
}\@ehc
}
% \end{macrocode}
%
% When comparing \cs{rqv@foo.sty} (information from a previous
% \latex/ run) with \cs{ver@foo.sty} (information from current run),
% we first call \cs{snap@trim@version} on the latter to clear away
% any idiosyncrasies in the contents.
% \begin{macrocode}
\def\snap@compare@versions#1{%
\begingroup
\@ifundefined{rqv@#1}{}{%
\edef\0{\csname rqv@#1\endcsname}%
\edef\1{\csname ver@#1\endcsname}%
\edef\1{\@xp\snap@trim@version\1 v0.0 v0.0 \@nil}%
\edef\@tempa{\@xp\snap@select\0 v0.0 v0.0 \@nil}%
\edef\@tempb{\@xp\snap@select\1 v0.0 v0.0 \@nil}%
\ifx\@tempa\@tempb
\else
\edef\@tempd{\@nx\snap@mismatch@a{#1}{\@tempa}{\@tempb}}%
\@xp\@tempd
\fi
}%
\endgroup
}
% \end{macrocode}
%
% Because \cs{ProvidesFile} is used in \fn{.fd} files which are
% normally read with special catcodes, there tend to
% be problems with whitespace characters being erroneously lost from
% the second argument. Since we have to put in a \cs{snap@check} call
% anyway, while we're at it let's fix a bug of this type that
% affected some older versions of \latex/.
% \begin{macrocode}
\def\ProvidesFile#1{%
\def\snap@checker{\snap@check{#1}}%
\begingroup
\aftergroup\snap@checker
\catcode`\ 10\catcode\endlinechar 10 %
\@makeother\/%
\@makeother\&%
\@ifnextchar[{\@providesfile{#1}}{\@providesfile{#1}[]}%
}
% \end{macrocode}
%
% \begin{macrocode}
\def\@pr@videpackage[#1]{%
\expandafter\xdef\csname ver@\@currname.\@currext\endcsname{#1}%
\ifx\@currext\@clsextension
\typeout{Document Class: \@gtempa\space#1}%
\else
\wlog{Package: \@gtempa\space#1}%
\fi
\snap@check{\@currname.\@currext}%
}
% \end{macrocode}
%
% The usual \cs{endinput} to ensure that random garbage at the end of
% the file doesn't get copied by \fn{docstrip}.
% \begin{macrocode}
\endinput
% \end{macrocode}
%
% \section*{To Do}
%
% \begin{itemize}
% \item Provide a test to distinguish between shared-use files and
% document-specific files? Document-specific files would be things
% like graphics files loaded via \cs{includegraphics} or book
% chapters loaded via \cs{include}. But there might also be something
% like \verb'\input{my-book-macros}' in the preamble. Maybe authors
% should be encouraged to put this after \verb'\begin{document}'? Or,
% even, after \verb'\begin{abstract}' so that the abstract will
% contain only lowest-common-denominator \LaTeX{} commands?
%
% The non-document-specific files most commonly loaded after
% \verb'\begin{document}' would be \fn{.fd} files, but there is also
% the possibility of autoloaded stuff (\fn{alatex} format).
% \end{itemize}
%
% \CheckSum{777}
% \Finale